Cooled shaft-furnace and stave-cooler to be used therefor

ABSTRACT

Stave-cooler for a lined shaft furnace, having a projection on its face which is inwardly directed in use for supporting the furnace lining, a plurality of passages for cooling fluid extending through the cooler in directions having at least a vertical (in use) component, at least some of the said passages extending for at least a substantial part of the vertical extent of the projection through that portion of the cooler which lies outwardly (in use) of the projection and a further fluid passage extending through the projection which has an inlet and an outlet in the outwardly directed (in use) face of the cooler and lies in a substantially horizontal plane.

STAVE-COOLER TO BE USED THEREFOR United States Patent 1 [111 3,881,860 1 Brandenburg May 6, 1975 COOLED SHAFT-FURNACE AND Primary ExaminerJohn J. Camby Attorney, Agent, or FirmStevens, Davis, Miller & Mosher [57] ABSTRACT Stave-cooler for a lined shaft furnace, having a projection on its face which is inwardly directed in use for supporting the furnace lining, a plurality of passages for cooling fluid extending through the cooler in directions having at least a vertical (in use) component, at least some of the said passages extending for at least a substantial part of the vertical extent of the projection through that portion of the cooler which lies outwardly (in use) of the projection and a further fluid passage extending through the projection which has an inlet and an outlet in the outwardly directed (in use) face of the cooler and lies in a substantially horizontal plane.

12 Claims, 10 Drawing Figures FIG. 5

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FIG. 6

COOLED SHAFT-FURNACE AND STAVE-COOLER TO BE USED THEREFOR The invention relates to a stave-cooler for a shaft furnace and also to a shaft furnace having one or more such coolers.

The invention will hereafter mainly be described in connection with its application to a blast furnace, but it is not restricted thereto and may be applied to other types of shaft furnaces which require cooling of the shaft.

Apart from other methods for cooling the wall of a blast-furnace, in recent years a special interest has arisen in constructions in which cooling panels having provision for cooling liquid circulation are attached to the inside of the steel mantle of the furnace. These cooling panels, referred to in English as stavecoolers, and in German literature referred to as Plattenkuhler, mainly consist of cast iron slabs, which, closely connected one to the other, are attached to the mantle. Also, in many cases in between these staves and the mantle there is provided a layer of refractory and thermally insulating material. Circulation passages are provided in the stave coolers, usually in the form of cast-in tubes, which are interconnected at the outside of the furnace to form an integrated system of passages. Through this system a cooling liquid, a cooling gas, or a mixture of cooling liquid and vapour can be circulated.

A separate problem caused by the application of this construction to a blast furnace lies in achieving adequate stability of the refractory lining adjacent the stave-coolers where the shaft narrows upwardly. This is because the lining in this region has no tendency to lean against the wall of the furnace because of its own weight and the weight of the load in the furnace, and special means are necessary to guarantee its stability, in order to prevent the refractory lining being insufficiently cooled, and consequently collapsing. Therefore in many cases the stave-coolers are provided with supporting cams, noses or other projections which extend into the furnace and serve to support the lining. As, however, these supporting projections extend further into the furnace than the remaining part of the stavecooler, heatflow concentrates particularly on them, making necessary special cooling which is obtained by means of a separate tube for cooling fluid extending through the projection, usually mainly in a horizontal plane.

Nevertheless it may happen that the heavy thermal load on the supporting cam causes it to collapse, in which case it is necessary to uncouple the tube extending through the projection from the cooling system, in order to prevent undesired penetration of the cooling medium into the furnace, and in order to keep operative the other elements which are coupled in series with this tube in the circulating system of the cooling medium. As a consequence of this however, the entire zone of the stave-cooler near the projection may be subject to insufficient cooling, giving rise to a real danger that the stave cooler itself is damaged, so that the mantle becomes too hot.

The present invention is concerned with the problem of avoiding or mitigating the dangers referred to above and with achieving better cooling of the supporting projection.

According to the invention there is provided a stavecooler for a lined shaft furnace, having a projection on its face which is inwardly directed in use for supporting the furnace lining, and a plurality of passages for cooling fluid extending through the cooler in directions having at least a vertical (in use) component, at least some of the said passages extending for at least a substantial part of the vertical extent of the projection through that portion of the cooler which lies outwardly (in use) of the projection. Thus the stave-cooler has at least two passages that extend in its longitudinal direction and extend behind the projection over a substantial part, e.g., at least half, of the dimension of the projection in that longitudinal direction. Preferably the stave-cooler has a further passage for cooling fluid extending through the projection, and this passage may lie in a horizontal plane including its inlet and outlet portions. Suitably inlet or outlet portions of the passages extending with a vertical component may be in the said horizontal plane, but it is preferred that they are adjacent the plane and both above and below it.

A limit to the extent to which the passages can extend behind the projection if as is at present usual, the p ro' jection is at the extreme upper end of the stave-cooler and the passages have their inlets or outlets in the outwardly directed face of the stave cooler. It is possible, when applying the present invention, to ignore the opinion that the projection should be at the extreme upper end of the stave-cooler, and to have it spaced from the upper end, preferably by at least the thickness of the cooler, whereby the passages in the cooler may extend in the cooler behind the projection over the full vertical extent of the projection.

Preferably the passages for cooling fluid are in the form of tubes, which may be cast in the stave-cooler.

If in a stave-cooler embodying the invention nevertheless separate cooling of the projection, should be reduced because of damage to the projection, then the projection yet remains somewhat cooled by the vertically extending passages which extend behind it in dependence on the rate of heat flow from the projection to the passages. Also as a result of extra cooling of the projection the danger of the projection being damaged may be considerably reduced, and hence also the danger of the reduction of the separate cooling of the projection.

When the projection is damaged because of superheating it should at any rate be prevented that the stave-cooler itself behind the projection is also damaged. Under very critical thermal load situations it may therefore even be advisable to connect the projection to the stave cooler as a separate, detachable and interchangeable element capable of being secured to the remainder of the cooler. In that case possibly a layer of insulating material can be provided between the projection and the stave cooler itself, reducing the thermal contact between the projection and the stave cooler almost entirely, whereby these two elements are cooled independently. Generally, however, the construction in which the projection and the stave cooler form one single casting will be preferred.

Usually the passage or passages through the projection is or are part of the circulation system for the vertically extending passages. In this case it is important that all passages within one and the same stave-cooler have equal internal diameters, in order to prevent the circulation of the cooling medium being unfabourably affected because of subsequent narrowings and widenings in the system. If, however, the cooling passages which extend behind the projection already guarantee a certain cooling of the projection the attraction of making the separate cooling of the projection a part of the circulation system through the rest of the stavecooler is diminished considerably.

In order to obtain better cooling of the projections it may be advisable to connect the passages through them to form a separate circulation system. In this case it is furthermore preferably to choose the cross-sectional areas, e.g., diameters of the passages through the projections larger than of those of the other passages through the stave-coolers, in order that extra forced cooling is obtained.

It should be remarked in this connection that the diameter of the passages through the stave-cooler determines the thickness of the stave-cooler, and if the stave-cooler should not be too thick, there is a restriction on the diameter of the passages. This however, does not apply to the projections which means that the passage that extends through the projection may well be larger. Where the stave-cooler is designed in this manner, it is preferable that the passage through the projections of all the stave-coolers in a furnace are connected to a separate circulation system for the passages extending with vertical components through the stavecoolers.

In conducting the connections of the passages through the furnace mantle special care should be taken that these connections remain gastight, and also that the strength of the steel mantle is not diminished in an unacceptable way.

To this end in practice the vertically extending passages are sometimes bent near their ends towards each other, in order that they can be conducted in combinations of two or three passage ends through the mantle. This construction creates, however, the risk especially that the projection leaves large parts of the stave cooler therebehind insufficiently cooled. This construction has also proved unattractive as to production cost, while also the three-dimensional shape of the passages increases the resistance of the circulation system and unduly influences the correct functioning of it. A construction of the stave-cooler is therefore preferred in which each of the passages extends in a flat plane, and in which the inlet and outlet of the passage through the projection extends alongside the inlets or outlets of the vertically extending passages. These inlets or outlets which extend alongside each other then can be conducted through one single opening in the mantle.

Several embodiments of the invention will be described by way of example with reference to the accompanying drawing, in which:

FIG. 1 schematically shows the connection of stavecoolers to the wall of a shaft furnace;

FIGS. 2, 4, 6 and 9 show in front-view upper parts re spectively of four stave-coolers embodying the invention;

FIGS. 3, 5, and 7 are respectively side-views of the stave-coolers of FIGS. 2, 4, and 6;

FIG. 8 is a cross-sectional view on the line VIIIVIII of FIG. 6; and

FIG. 10 is a vertical section through the stave-cooler of FIG. 9.

In FIG. 1 two stavecoolers 2 and 3 are connected to a steel mantle 1 of a blast furnace by means of bolt connections 4, 5, 6. A lining 7 of the furnace has been shown schematically against the stave-coolers. Within the stave-coolers tubes (not shown) extend, of which the ends 8, 9, 10 traverse the mantle, these ends from the several stave-coolers being mutually interconnected. On the inner face of the stave-cooler 3 a supporting projection 1 1, is provided for support of the refractory lining lying above it. The projection is a nose or cam projecting from the inner face of the stavecooler and extending the full width of the face.

Turning to FIGS. 2 and 3, tubes 12, 13, 14, 15 for cooling fluid extend through the stave-cooler in the longitudinal direction i.e., vertically in use, and have inlets and outlets 16, 17, 18, 19 in the outer face of the cooler. A tube 22 for cooling fluid, extending in a transverse (horizontal) direction through the supporting projection 11, posesses an inlet and outlet 20, 21. The tubes 12, 13, 14, 15 are in vertical planes, and the tube 22 in a horizontal plane.

As shown outlets 17, 18, 20, 21 are situated in the same horizontal plane, which means that tubes 13, 14 extend in the stave-cooler behind the projection 11 over about half the vertical extent of the projection.

In the different embodiment of FIGS. 4 and 5, vertically extending cooling tubes 24, 25 have exits 28, 29 situated above exits 31, 32 of a cooling tube 33 which extends through supporting cam 11. Outlets 27 and 31, respectively 30 and 32 have been situated sufficiently close to each other that the pairs of tube-ends can traverse the mantle 1 through one single opening. In this way a simpler pattern of openings through the mantle 1 is obtained, while also the supporting projection 11 is better cooled.

In FIGS. 6, 7 and 8 another embodiment is shown in which the supporting projection 11 has been shifted downwardly with respect to the upper end of the stavecooler by a distance greater than the thickness of the stave-cooler from its inner face (away from the projection) to its outer face. As a result the vertical cooling tubes 34,35,36, 37 extend over the full vertical extend of the projection 11 up to their outlets 38, 39, 4t), 41 which are situated in one horizontal line. A cooling tube 44 through the supporting projection 11 has a curved shape such that it extends over the entire width of the projection 11 and yet debouches in outlets 42, 43 in between the vertical tubes 34, 35, 36, 37.

FIGS. 9 and 10 show yet another stave-cooler embodying the invention which in general corresponds to that of FIGS. 6 to 8, the difference, however, being that the fixed supporting projection 1 1 has been replaced by a interchangeable supporting projection 56 which is shown mounted on the stave-cooler, and is supported by a rib 57. By providing insualating material in between the supporting cam 56 and the stave-cooler 3, two independently cooled systems, the stave-cooler 3 and the projection 56 are obtained, which may be of importance in case the projection 56 burns off. The possibility even has now been provided of, after the furnace has been so-called deep blown replacing the defective supporting projection by a new one.

It should be remarked that it is usual with furnaces that have been provided with a lintel-ring, between the bosh and the shaft to have the upper most stave-coolers of the bosh extend beyond the lintel-ring. These stavecoolers in principle may be designed in a similar way to those shown in FIGS. 2 to 5, in which case, however, the supporting projection and the part of the stavecooler behind it should be situated in a position which is radially shifted over a distance corresponding to the radial dimension of the supporting projection.

Insulation provided between the projection and the portion of the stave cooler behind it, on the one hand may minimize heating of the projection by the cooler in cases where the projection is more strongly cooled by its own cooling system than the remainder of the cooler, and on the other hand may minimize heating of the cooler behind the projection if the projection is damaged so that its own cooling system fails. In the lat- 'ter case especially the cooling of the portion behind the cherewith in the horizontal row thereabove, having a nrojection on its face which is inwardly directed in use :or supporting the furnace lining, a plurality of passages br cooling fluid extending through the cooler in direc- :ions having at least a vertical (in use) component, at east some of the said passages extending for at least a :ubstantial part of the vertical extent of the projection ihrough that portion of the cooler which lies outwardly :in use) of the projection and a further fluid passage ex- :ending through the projection which has an inlet and in outlet in the outwardly directed (in use) face of the :ooler and lies in a substantially horizontal plane.

2. Stave-cooler according to claim 1 wherein the said )assages each extend in a vertical plane from an inlet toan outlet, both of which. are in the outwardly directed (in use) face of the cooler.

3. Stave-cooler according to claim 1 wherein the said passages extending with at least a vertical component have inlets or outlets adjacent the said horizontal plane and both above and below it.

4. Stave-cooler according to claim 1 wherein portions of the said passages extending over at least a substantial portion of the vertical extent of the projection, which portions are adjacent the outlets of the passages, lie in the said horizontal plane adjacent the inlet and outlet portions of the passage through the projection.

5. Stave-cooler according to claim 1 wherein the said passage extending through the projection is of larger cross-sectional area than the other passages.

6. Stave-cooler according to claim 1 wherein the pro- I jection is spaced from the upper end of the cooler.

7. Stave-cooler according to claim 6 wherein the projection is spaced inwardly by at least the thickness of the cooler from the upper end of the cooler.

8. Stave-cooler according to claim 1 wherein at least some of the said passages extending with a vertical component extend through the cooler over the whole of the vertical extent of the projection.

9. Stave-cooler according to claim 1 wherein all the said passages are provided by tubes.

10. Stave-cooler according to claim 1 wherein the projection is detachably secured or securable to the remainder of the cooler.

11. Shaft furnace having one or more stave-coolers according to claim 1.

12. Shaft furnace according to claim 11 wherein the said passage through the projection is connected to a different fluid circulation circuit from the said passages extending with a vertical component. 

1. Stave-cooler for a lined shaft furnace, suited for being provided as one of a series of aligned members in horizonal rows to be cooled, the members of the horizontal rows being aligned to provide vertical rows, vertical pipes for passing a coolant accommodated by each member and with external pipes connecting the pipes of the cooling members of one horizontal row with the vertical pipes of the cooling members vertically aligned therewith in the horizontal row thEreabove, having a projection on its face which is inwardly directed in use for supporting the furnace lining, a plurality of passages for cooling fluid extending through the cooler in directions having at least a vertical (in use) component, at least some of the said passages extending for at least a substantial part of the vertical extent of the projection through that portion of the cooler which lies outwardly (in use) of the projection and a further fluid passage extending through the projection which has an inlet and an outlet in the outwardly directed (in use) face of the cooler and lies in a substantially horizontal plane.
 2. Stave-cooler according to claim 1 wherein the said passages each extend in a vertical plane from an inlet to an outlet, both of which are in the outwardly directed (in use) face of the cooler.
 3. Stave-cooler according to claim 1 wherein the said passages extending with at least a vertical component have inlets or outlets adjacent the said horizontal plane and both above and below it.
 4. Stave-cooler according to claim 1 wherein portions of the said passages extending over at least a substantial portion of the vertical extent of the projection, which portions are adjacent the outlets of the passages, lie in the said horizontal plane adjacent the inlet and outlet portions of the passage through the projection.
 5. Stave-cooler according to claim 1 wherein the said passage extending through the projection is of larger cross-sectional area than the other passages.
 6. Stave-cooler according to claim 1 wherein the projection is spaced from the upper end of the cooler.
 7. Stave-cooler according to claim 6 wherein the projection is spaced inwardly by at least the thickness of the cooler from the upper end of the cooler.
 8. Stave-cooler according to claim 1 wherein at least some of the said passages extending with a vertical component extend through the cooler over the whole of the vertical extent of the projection.
 9. Stave-cooler according to claim 1 wherein all the said passages are provided by tubes.
 10. Stave-cooler according to claim 1 wherein the projection is detachably secured or securable to the remainder of the cooler.
 11. Shaft furnace having one or more stave-coolers according to claim
 1. 12. Shaft furnace according to claim 11 wherein the said passage through the projection is connected to a different fluid circulation circuit from the said passages extending with a vertical component. 